Key Operation Research Articles

Complete Coverage Path Planning Based on Improved Genetic Algorithm for Unmanned Surface Vehicle

Complete Coverage Path Planning (CCPP) is a key technology for Unmanned Surface Vehicles (USVs) that require complete coverage on the water surface, such as water sample collection, garbage collection, water field patrol, etc. When facing complex and irregular boundaries, the traditional CCPP-based boustrophedon method may encounter many problems and challenges, such as multiple repeated regions, multiple turns, and the easy occurrence of local optima. The traditional genetic algorithm also has some shortcomings. The fixed fitness function, mutation operator and crossover operator are not conducive to the evolution of the population and the production of better offspring. In order to solve the above problems, this paper proposes a CCPP method based on an improved genetic algorithm, including a stretched fitness function, an adaptive mutation operator, and a crossover operator. The algorithm combines the key operators in the fireworks algorithm. Then, the turning and obstacle avoidance during the operation of the Unmanned Surface Vehicle are optimized. Simulation and experiments show that the improved genetic algorithm has higher performance than the exact unit decomposition method and the traditional genetic algorithm, and has more advantages in reducing the coverage path length and repeating the coverage area. This proves that the proposed CCPP method has strong adaptability to the environment and has practical application value in improving the efficiency and quality of USV related operations.

Revolutionizing the Application of Automatic Inspection System for Industrial Parts Using AI Machine Vision Technology

This paper addresses the challenges of large data management, prolonged operation times, and low detectionefficiency encountered in automatic detection systems. To overcome these issues, we propose a novel research and application method utilizing AI machine vision technology. The methodology employs the Pulse-Coupled Neural Network (PCNN) algorithm for analyzing machine control points, enhancing system reliability and detection efficiency. Furthermore, a three-stage sliding table mechanism is implemented to facilitate seamless operation restarts. Notably, our approach significantly reduces the time required for key operations, such as feeding, imaging, decision-making, on-site inspection, and re-inspection, all within 5 seconds and 1 meter distance. It supports high-precision dynamic identification, detection, and correction of errors during high-speed movement, thereby enhancing overall system performance. The experimental results demonstrate exceptional accuracy, particularly in detecting small parts measuring 28.87 mm in length and 12.36 mm in width, achieving an impressive precision of 0.04 mm. Additionally, our system boasts meticulous hardware selection, robust software stability, and high-performance capabilities, culminating in improved detection efficiency and accuracy. This research not only contributes novel ideas and results but also holds significant commercial value in industrial applications. Overall, our proposed methodology represents a noteworthy advancement in automatic inspection systems, offering superior performance and reliability compared to existing approaches.

A blockchain-based academic degree attestation system

ABSTRACT We propose a novel blockchain-based academic degree verification system. The system relies on a smart contract deployed on the Ethereum blockchain platform. The system protects the privacy of the students who have been verified without the need of encryption, and hence, avoid the complexity of security key management and the potential disaster if the keys are stolen or revealed. The amount of degree data is also designed to be minimum for proper verification. All operations on the critical path of the system are automated without any human intervention. However, the system does assume that the organization would stand behind the proposed system to ensure the system's integrity. The system is open to anyone who wishes to verify the degree of a student. To prevent spamming and to support the long-term sustainability of the system, a small fee is charged for each verification request. A portion of the fees collected is immediately credited to the participating schools. To facilitate automated school enrollment into the system, any school may request to enroll by placing a significant amount of stake in ETH. The stake can be refunded when the school decides to leave the system. However, if the school is blacklisted due to misbehavior, the stake is confiscated. This design strongly discourages adversaries from abusing the system. The performance of the system is fully characterized with regard to the gas consumption of key operations in various use cases. We demonstrate that the system is conducive for long-term sustainability.

Strain analysis and non-destructive monitoring of the two-stage hydraulic-driven piston compressor for hydrogen storage

High-pressure gas storage is an important means of hydrogen application in the transportation industry, especially in hydrogen refuelling stations. The hydrogen compressor is the most crucial dynamic component for high-pressure gas storage in hydrogen refuelling stations. An effective control system is required to guarantee the compressor operates safely and efficiently, which is based on the safe and efficient monitoring of the operating condition of the compressor. However, significantly limited literature has been provided for the hydraulic-driven piston compressor. In this paper, a non-destructive testing method for monitoring the dynamic pressure by strain gauge in the hydraulic-driven piston compressor is proposed. The relationship between the strain of the cylinder head and key operating parameters is obtained through finite element analysis, based on which the optimal location for the pressure monitoring is identified. The proposed non-destructive testing method is validated by experiments of a two-stage hydraulic-driven piston compressor. The strain analysis indicates that the circumferential strain in the cylinder head has a good linear relationship with the in-cylinder gas pressure with a value above 99.6 %. The deformation of the four monitoring positions is almost unchanged with a maximum deviation of 0.5 % under different piston positions. A high uniformity of the circumferential strain of the cylinder head is observed from the analysis. Experimental results indicate that the proposed non-destructive monitoring method is effective in obtaining the dynamic pressure in-cylinder during the compressor operation with a maximum deviation of 5.13 % and an average deviation below 2.01 %.

A high-rate and long-life zinc-bromine flow battery

Zinc-bromine flow batteries (ZBFBs) offer great potential for large-scale energy storage owing to the inherent high energy density and low cost. However, practical applications of this technology are hindered by low power density and short cycle life, mainly due to large polarization and non-uniform zinc deposition. In this work, a systematic study is presented to decode the sources of voltage loss and the performance of ZBFBs is demonstrated to be significantly boosted by tailoring the key components (electrolyte, electrodes, and membranes) and operating conditions (flow rate and temperature). Results show that the optimized battery exhibits an energy efficiency of 74.14 % at a high current density of 400 mA cm−2 and is capable of delivering a current density up to 700 mA cm−2. Furthermore, a peak power density of 1.363 W cm−2 and a notable limiting discharge current density of ∼1.5 A cm−2 are achieved at room temperature. More remarkably, the battery is stably operated for over 1200 cycles (∼710 h) at 200 mA cm−2 and 60 mAh cm−2, which sheds light on the development of high-rate and long-life ZBFBs for next-generation energy storage.

Demonstration of charge-hold-vent (CHV) and no-vent-fill (NVF) in a simulated propellent storage tank during tank-to-tank cryogen transfer in microgravity

The space exploration from a low earth orbit to a high earth orbit, then to Moon, Mars, and possibly asteroids and moons of other planets is one of the biggest challenges for scientists and engineers for the new millennium. The enabling of in-space cryogenic rocket engines and the Lower-Earth-Orbit (LEO) cryogenic fuel depots for these future manned and robotic space exploration missions begins with the technology development of advanced cryogenic thermal-fluid management systems for the propellant transfer line and storage tank system. One of the key thermal-fluid management operations is the chilldown and filling of the propellant storage tank in space. As a result, highly energy efficient, breakthrough concepts for quenching heat transfer to conserve and minimize the cryogen consumption during chilldown have become the focus of engineering research and development, especially for the deep-space mission to Mars. In this paper, we introduce such thermal transport concepts and demonstrate their feasibilities in space for cryogenic propellant storage tank chilldown and filling in a simulated space microgravity condition on board an aircraft flying a parabolic trajectory. In order to maximize the storage tank chilldown thermal efficiency for the least amount of required cryogen consumption, the breakthrough quenching heat transfer concepts developed include the combination of charge-hold-vent (CHV) and no-vent-hold (NVF). The completed flight experiments successfully demonstrated the feasibility of the concepts and discovered that spray cooling combined with hold and vent is more efficient than the pure spray cooling for storage tank chilldown in microgravity. In microgravity, the data shows that the CHV thermal efficiency can reach 39.5%. The CHV efficiency in microgravity is 6.9% lower than that in terrestrial gravity. We also found that pulsing the spray can increase CHV efficiency by 6.1% in microgravity.

Pilot-scale electrochemical advanced oxidation (EAOP) system for the treatment of Ni-EDTA-containing wastewater

Electrochemical advanced oxidation processes (EAOP) have shown great potential for the abatement of complexed heavy metals, such as metal-EDTA complexes, in recent studies. While removal of metal-EDTA complexes has been extensively examined in bench-scale reactors, much less attention has been given to the efficacy of this process at larger scale. In this study, we utilize a 72 L pilot-scale continuous flow system comprised of six serpentine flow channels and 90 pairs of flow-through electrodes for the degradation of Ni-EDTA complexes and removal of Ni from solution. The influence of a range of key operating parameters including flow rate, current density and initial Ni-EDTA concentration on rate and extent of Ni-EDTA degradation and Ni removal were examined. Our results showed that at a feed flow rate of 36 L h−1, current density of 5 mA cm−2 and initial Ni-EDTA concentration of 1 mM, the pilot-scale system achieved 74 % total Ni removal, 78 % total EDTA removal and 40 % TOC removal with energy consumption of 13.6 kWh m−3 order−1 and energy efficiency of 7.9 g kWh−1 for total Ni removal. A mechanistically-based kinetic model, which was developed in our previous bench-scale study, provides a satisfactory description of the experimental results obtained in the pilot-scale unit. Long term operation of the pilot-scale unit resulted in corrosion of PbO2 anode along with inorganic scaling as well as organic fouling on the PbO2 surface resulting in an obvious decline in Ni-EDTA degradation. Overall, the results of this study suggest that large scale anodic oxidation of wastewaters containing metal-organic complexes is an effective means of degrading organic ligands thereby enabling removal of the metal at the cathode. However, additional efforts are required to enhance the durability of the anode material and reduce material costs and energy consumption.

Operator parallel optimization strategy for distributed databases

With the continuous development of network technology, the scale of data has shown explosive growth, which leads gradually to replacing traditional single machine databases with distributed databases. Distributed databases solve large-scale data storage problems through collaborative work among nodes, but due to increased communication costs between nodes, its query efficiency is not as good as a standalone database. In a distributed architecture, the data of storage nodes is only used as redundancy for multiple backups, providing data recovery in case of system failure, and it is not utilized to improve query efficiency. In response to the above issues, this article proposes an operator parallel optimization strategy for distributed databases. By splitting key physical operators, the split sub requests are evenly distributed to multiple nodes in the storage layer, which are processed in parallel by multiple nodes, thereby reducing query response time. The above strategy has been applied on distributed database CBase, and experiments have shown that the parallel optimization strategy proposed in this paper can significantly shorten SQL request query time and improve system resource utilization.

PimPam: Efficient Graph Pattern Matching on Real Processing-in-Memory Hardware

Graph pattern matching is powerful and widely applicable to many application domains. Despite the recent algorithm advances, matching patterns in large-scale real-world graphs still faces the memory access bottleneck on conventional computing systems. Processing-in-memory (PIM) is an emerging hardware architecture paradigm that puts computing cores into memory devices to alleviate the memory wall issues. Real PIM hardware has recently become commercially accessible to the public. In this work, we leverage the real PIM hardware platform to build a graph pattern matching framework, PimPam, to benefit from its abundant computation and memory bandwidth resources. We propose four key optimizations in PimPam to improve its efficiency, including (1) load-aware task assignment to ensure load balance, (2) space-efficient and parallel data partitioning to prepare input data for PIM cores, (3) adaptive multi-threading collaboration to automatically select the best parallelization strategy during processing, and (4) dynamic bitmap structures that accelerate the key operations of set intersection. When evaluated on five patterns and six real-world graphs, PimPam outperforms the state-of-the-art CPU baseline system by 22.5x on average and up to 71.7x, demonstrating significant performance improvements.

Exergy analysis of off-design performance in solar-aided power generation systems: Evaluating the rationality of using part-load operation solution of coal-fired plants

Solar aided coal-fired power generation (SAPG) technology has been proven to be an effective way of renewable energy utilization. However, the efficiency of coal-fired units declines at partial loads, and solar inputs may further force the system to deviate from its design condition. In particular, part-load operation solutions for coal-fired units (PLOS) are conventionally applied to the SAPG system, a practice whose appropriateness has not yet been thoroughly evaluated. This paper, therefore, selects a 330 MW SAPG plant as a case study to conduct an exhaustive exergy analysis under off-design conditions. The findings indicate that the governing stage of the steam turbine and the slip-pressure operation are the main contributors to the efficiency degradation at partial loads. In addition, solar input resulted in significant changes in key operating parameters, such as exhaust flow rate and the pressure of each turbine stage. Merely adopting the PLOS for SAPG systems results in a marked increase in standard coal consumption by 0.99, 2.82, and 3.63 g/kWh at 50 %, 40 %, and 30 % load, respectively. However, the introduction of solar energy presents the potential to operate the unit more efficiently, particularly when valve point conditions are optimally adjusted. For instance, upon input of 28 MW solar thermal power, the #3 valve point condition shifted from a load of 321 MW–330 MW, achieving a reduction in standard coal consumption by 0.96 g/kWh, compared to the design condition of the original coal-fired unit. This study underscores the irrationality of directly applying PLOS from coal-fired units to SAPG system without tailored adjustments for solar integration.

A facile strategy for designing hollow-porous polymer microparticles with tunable structures

Biodegradable hollow-porous microparticles have shown great potentials in chemical and biomedical areas owing to their distinctive structural attributes. Herein, a simple but instructive strategy was proposed to construct hollow-porous polylactic acid (PLA) microparticles in one-step based on electrohydrodynamic atomization technology. Hollow-porous microparticles with fusiform, red blood cell and spherical shapes were successfully fabricated with production rates of 70 mg/h, 30 mg/h and 105 mg/h. A formation map in terms of flow rate ratio and PLA concentration was obtained to demonstrate the operating regions. Effects of key operating parameters were studied, showing that high voltage (11.4 kV−12.4 kV) and low PLA concentration conditions (2.5 %−3.5 %) are preferred to get well-structured particles. The evolutions of Taylor cone and atomization state were also explored experimentally and numerically to further understand the process. The prepared microparticles exhibit excellent sustained release performance and high encapsulation rate (>90 %). This strategy offers a satisfactory one-step method for preparing various structured hollow-porous polymer particles as drug carriers.

A novel intercooling carbon dioxide capture process using ionic liquids with ultra-low energy consumption

This study focuses on the use of ionic liquids as solvents for carbon dioxide capture due to their low energy demand. We screened an ideal ionic liquid, 1-ethyl-3-methylimidazolium bis[trifluoromethylsulfonyl]imide ([emim][Tf2N]), based on its excellent absorption capacity and low viscosity. We performed thermodynamic modeling of the gas-liquid phase equilibrium to lay the foundation for process simulation. A basic process was designed for benchmarking performance, and various cases were compared by adjusting key operating parameters such as pressure and temperature. The results showed that the lowest specific capture energy achieved was 1.12 GJ/t at 20 bar and 5 °C. However, further improvements in energy performance were constrained by reduced absorption capacity and increased viscosity resulting from lower operating pressures and temperatures. To address these constraints, we proposed a novel process that optimized the temperature profile in the absorption column by dividing it into two sections with intercooling. This approach did not require significant changes to the base case but offered multidimensional benefits, including reduced energy demand and associated equipment costs. The specific capture energy was further reduced to 1.04 GJ/t. Economic analysis indicated that the capture cost at a production scale of 13.7 kt/a was 206 $/t but had the potential to be reduced to 82 $/t. The costs associated with compressors were found to be the major contributors to both equipment and capture costs. The proposed novel process demonstrates promising benefits and highlights the importance of further investigation into low-pressure operation.

Beetaloo or bust: the route to commercial success for an Australian shale play

There is a huge unconventional shale gas resource in the remote heart of the Northern Territory with the potential to trigger big new gas developments in Darwin, including export liquefied natural gas (LNG), and underpin the chronically undersupplied East Coast market. And yet despite this promise, the Beetaloo is not universally viewed as a viable commercial project. Nonetheless, the Beetaloo is one of the hottest topics in Australia’s upstream sector, and two of its key operators, Tamboran and Empire, are closing in on final investment decision (FID) for initial gas production. So why are many in the market still sceptical the play will work? To create a definitive answer, we investigate the key factors required to make the Beetaloo commercially viable. We will evaluate what a Beetaloo gas project could look like across a range of resource sizes, estimated ultimate recovery (EUR) from analogue production profiles, and well costs. The work aims to understand the key cost barriers and price hurdles that need to be broached for economic success. From here we can determine the full range of economic pitfalls and potential rewards that lie in wait for ambitious Beetaloo operators.

Triangular cross-section beam splitters in silicon carbide for quantum information processing

AbstractTriangular cross-section color center photonics in silicon carbide is a leading candidate for scalable implementation of quantum hardware. Within this geometry, we model low-loss beam splitters for applications in key quantum optical operations such as entanglement and single-photon interferometry. We consider triangular cross-section single-mode waveguides for the design of a directional coupler. We optimize parameters for a 50:50 beam splitter. Finally, we test the experimental feasibility of the designs by fabricating triangular waveguides in an ion beam etching process and identify suitable designs for short-term implementation.

DNA Steganography: Embedding the Secret Messages Using Glass Stack Method and Detecting Errors Made by Different Attacks

Cyber threats pose a significant challenge to protecting cloud-based health data, including DNA sequences and patient information. Steganography is a well-known solution to this problem. Recent studies have limitations, such as not reconstructing the cover or enlarging the original sequence, increasing personal data security risks. In this study, we provide a novel data-hiding technique that uses a secret key, bit padding, and exclusive OR (XOR) operation to insert secrets into a pre-processed DNA sequence. The message encryption and pre-processing of the cover are performed using a new glass stack pattern technique. The message encryption and pre-processing processes using the new glass stack pattern method increase the security and robustness of the system. The method embeds 3 bits per nucleotide which is greater than the existing schemes. It has a relatively small DNA expansion which is 50% and has a low risk of breaking security. The method also preserves the biological properties of DNA sequences. Additionally, a parity check approach further improves security by thwarting attacks like man-in-the-middle, chosen stego, and modification attacks that alter the stego DNA. These advances improve the system's overall security capabilities. The experimental findings demonstrate that the suggested method reconstructs the cover, healthcare data, and DNA sequence properly and error-free, and outperforms competing algorithms on all performance metric dimensions. Highlights The scheme implants a maximum of 3 bits per nucleotide with a small expansion. Its cover pre-processing and message encryption using a glass stack pattern makes strong security. The scheme can detect and fix changed bits caused by attacks. A very low cracking probability shows strong security and robustness. The biological properties of the stego DNA sequence are preserved by this scheme.

Environmental and Technological Aspects of the Functioning of Municipal Solid Waste Recycling Complexes (on the Example of the Moscow Region)

The existing scheme, key operations and technologies used in the company for sorting and processing municipal solid waste in the Moscow region have been considered. The features of waste streams entering the waste processing system have been studied, quantitative and qualitative characteristics of the morphological composition have been presented, actual data on the composition of pollutant emissions generated at different stages of waste sorting and processing have been analyzed, the most problematic areas and priority eco-toxicants have been identified.

Novel nanostructure approach for antibiotic decomposition in a spinning disc photocatalytic reactor

Conventional wastewater treatment processes are often unable to remove antibiotics with resistant compounds and low biological degradation. The need for advanced and sustainable technologies to remove antibiotics from water sources seems essential. In this regard, the effectiveness of a spinning disc photocatalytic reactor (SDPR) equipped with a visible light-activated Fe3O4@SiO2-NH2@CuO/ZnO core–shell (FSNCZ CS) thin film photocatalyst was investigated for the decomposition of amoxicillin (AMX), a representative antibiotic. Various characterization techniques, such as TEM, FESEM, EDX, AFM, XRD, and UV–Vis-DRS, were employed to study the surface morphology, optoelectronic properties, and nanostructure of the FSNCZ CS. Key operating parameters such as irradiation time, pH, initial AMX concentration, rotational speed, and solution flow rate were fine-tuned for optimization. The results indicated that the highest AMX decomposition (98.7%) was attained under optimal conditions of 60 min of irradiation time, a rotational speed of 350 rpm, a solution flow rate of 0.9 L/min, pH of 5, and an initial AMX concentration of 20 mg/L. Moreover, during the 60 min irradiation time, more than 69.95% of chemical oxygen demand and 61.2% of total organic carbon were removed. After the photocatalytic decomposition of AMX, there is a substantial increase in the average oxidation state and carbon oxidation state in SDPR from 1.33 to 1.94 and 3.2, respectively. Active species tests confirmed that ·OH and ·O2− played a dominant role in AMX decomposition. The developed SDPR, which incorporates a reusable and robust FSNCZ CS photocatalyst, demonstrates promising potential for the decomposition of organic compounds.

Evaporating crystallization effect of ammonium sulfate at atmospheric pressure under the action of ultrasound

Ultrasound enhanced evaporating crystallization has been proposed to solve the problems of low crystallization yield and uneven particle size in the evaporating crystallization process of ammonium sulfate solution at atmospheric pressure. The effects of key operating parameters, including the ultrasound power, stirring speed, pH value, and ultrasound time, on the yield of ammonium sulfate product and the duration of solid–liquid transformation time are studied. The results show that the ultrasound crystallization can increase the ammonium sulfate yield by 52.9 %, reduce the solid–liquid transformation time of ammonium sulfate by 10 %, and obtain ammonium sulfate products with higher crystallinity and more uniform particle size. Ultrasound promotes the crystallization of ammonium sulfate by enhancing the transfer of heat in the solution and reducing the supersolubility of the ammonium sulfate solution from 937.5 g/L to 833.33 g/L. This study provides experimental justification for the use of ultrasound in atmospheric evaporative crystallization.

Enabling low-latency IoT communication for resource-constrained devices with the led cipher and decipher protocol

Block cipher algorithms are crucial for securing applications on resource-constrained devices. This paper introduces the modified light encryption device (MLED) cipher-decipher architecture, specifically designed to accommodate both 64-bit and 128-bit key sizes while maintaining a consistent 64-bit block and data size. MLED comprises 8-step and 12-step processes for MLED-64 and MLED-128 modules, respectively. Each stage involves a four-round operation followed by an add-round key operation. The add constant module (ACM) and mixed column modules (MCMs) within the round operation have been optimized for improved latency and throughput. Performance analysis reveals that MLED-64/128 requires less than 1% of the available slices and operates at 125 MHz on the Artix-7 FPGA. It achieves delays of 7.5 and 12.5 clock cycles for MLED-64 and MLED-128, respectively, translating to throughputs of 1366.5 Mbps and 819.89 Mbps. Additionally, MLED-64/128 exhibits hardware efficiencies of 2.373 and 0.986 Mbps/slice, respectively. Comparative evaluations with existing LED and other block ciphers (BCs) demonstrate that MLED-64/128 achieves significant improvements in latency, throughput, and efficiency, making it a compelling choice for securing resource-constrained IoT applications.

Efficient removal of oxytetracycline antibiotic from aqueous media using UV/g-C3N4/Fe3O4 photocatalytic process

Residual pharmaceuticals in the environment are a class of emerging pollutants that endanger human health. Tetracycline's family, including oxytetracycline (OTC), are known as one of the most produced and consumed antibiotics worldwide. The g-C3N4/Fe3O4 nanocomposite with high level of catalytic efficiency features suitable performance in water/wastewater treatment. Therefore, in the present study, this nanocomposite was applied to remove the oxytetracycline from the aqueous environment. In this research study, g-C3N4/Fe3O4 nanocomposite (serving as catalyst) was initially synthesized by a simple hydrothermal method. The effect of key operating parameters such as initial solution pH, dose of catalyst, contact time and initial concentration of OTC in aqueous solutions was investigated under UV irradiation. In addition, COD and TOC tests, the kinetics and the effect of radical scavengers on the applied photocatalytic process were all evaluated. The maximum removal efficiency of OTC (99.8 %) was achieved under the following conditions: neutral solution pH 7; catalyst dose, 0.7 g/L; and an initial OTC concentration of 5 mg/L. The data showed that the kinetics of the reaction followed the first-order model with R2 of 0.9755. The respective COD and TOC efficiency values for the applied photocatalytic process were determined to be 87 and 59 %, respectively. In addition, the lowest removal efficiency of OTC was observed in the presence of tert-butanol radical scavengers, and OH radicals played a main role. The UV/g-C3N4/Fe3O4 photocatalytic process proved to be highly efficient for the removal of OTC antibiotic and could be potentially applied for the removal of other pollutants from aqueous solutions.